It is known to provide a drilling rig assembly with derrick and pipe loader assemblies adapted to be moved so as to align drill pipe sections and the like. Conventional derrick and pipe loader assemblies on drilling rig assemblies, however, suffer from one or more disadvantages. For example, conventional derrick assemblies are either rack-and-pinion or dual mast assemblies. As a result, conventional derrick assemblies having a rack-and-pinion assembly can provide downward force on a drill pipe section, but the rack must be offset from the longitudinal axis or hole center causing undesirable overhung load and limited open space for working and tooling. Conventional derrick assemblies having a dual mast assembly use a cable system which avoids overhung loads but is not capable of providing any downward force on the drill pipe sections without undesirable supplemental cable systems. Conventional derrick and pipe loader assemblies also do not have a pipe loader assembly pivot axis that is co-linear with the derrick assembly pivot axis. As a result, conventional derrick and pipe loader assemblies cannot align drill pipe sections at all derrick mast angles and locations without separate adjustment of each assembly. Conventional derrick and pipe loader assemblies are also undesirably expensive, complex and heavy. In addition, in conventional drilling rig assemblies, the pipe loader assembly is not integral with the drilling rig skid. Conventional drilling rig assemblies also have derrick assemblies and pipe loader assemblies that cannot be adjusted together as a unit. Further, in conventional drilling rig assemblies, the pipe loader assembly is not disposed directly beneath the derrick assembly and it must be adjusted separately from the derrick assembly when the derrick assembly is adjusted.
It would be desirable, therefore, if an apparatus and method for a drilling rig assembly could be provided that would include a rack-and-pinion, dual mast derrick assembly adapted to provide downward force to a drill string section, avoid overhung load and maximize open space for working and tooling. It would also be desirable if such an apparatus and method could be provided that would have a pipe loader assembly pivot axis that is co-linear with the derrick assembly pivot axis. It would be further desirable if such an apparatus and method could be provided that would align drill pipe sections at all derrick mast angles and locations. It would be still further desirable if such an apparatus and method could be provided that would be inexpensive, simple and light. In addition, it would be desirable if such an apparatus and method could be provided that would integrate the pipe loader assembly with the drilling rig skid. It would also be desirable if such an apparatus and method could be provided that would permit the derrick assembly and the pipe loader assembly to be adjusted together as a unit. Further, it would be desirable if such an apparatus and method could be provided in which the pipe loader assembly is disposed directly beneath the derrick assembly and it does not require separate adjustment when the derrick assembly is adjusted.